It is often difficult for users to compose queries that provide useful results when searching the Web or other document sources. Even though the desired results of a query may be clear, from a human perspective, a query-based search may return results that are either irrelevant or not authoritative enough. A few examples of such searches are those that are based on queries having key terms that do not match the key terms in the desired result documents, queries that are too general, or queries that are too specific.
Two techniques that may be used to improve user-submitted queries are query reformulation and query suggestion. Query reformulation is a process by which a user-submitted query is improved by correcting misspelled words, suggesting more frequently used terms that are slightly different from the original terms, and so on. Query reformulation is often performed automatically, without explicit interactions with the user.
Query suggestion is a technique for assisting users to interactively refine queries. Existing query suggestion techniques typically suggest alternate queries based on each alternate query's similarity or relevance to the original user-submitted query.